A. Field of the Invention
The invention is an edge finder and method for orienting a work piece, a work-holding feature, or a cutting tool with respect to the spindle of a machine tool. An example of a machine tool is a milling machine or a lathe. The ‘work piece’ is the object to be cut using the machine tool.
In the case of a milling machine, a work-holding feature secures the work piece with respect to the spindle of the machine tool. Examples of work-holding features are a table of the machine tool and a vise. A cutting tool is attached to the spindle and rotates with the spindle to cut the work piece. The edge finder of the Invention locates the work-holding feature or the work piece with respect to the spindle of the milling machine.
In the case of a lathe, the work piece is attached to the spindle of the lathe and rotates with the spindle. A cutting tool that is not attached to the spindle cuts the rotating work piece. The edge finder of the Invention locates the cutting tool of the lathe with respect to the lathe spindle or the work piece.
Although this document discusses the edge finder of the Invention in the context of a milling machine having a rotating spindle and a stationary work piece, the Invention applies equally to a lathe having a moving work piece and a stationary cutting tool, or to a machine tool in which both the work piece and the cutting tool move.
B. Statement of the Related Art
As used in this document, machining is the subtractive shaping of a work piece to remove material from the work piece where the relative motion between a cutting tool and the work piece is defined by a machine tool. Accurate machining requires that the machinist accurately align the rotating spindle of the milling machine, which holds the cutting tool, and the work piece.
A milling machine includes a table to which a work piece may be attached. The table is movable in the ‘X’ and ‘Y’ directions in an X-Y-Z coordinate system. The spindle is configured for rotation. A milling cutter, such as an end mill, slab mill, side-and-face cutter, involute gear cutter, thread mill, face mill, fly cutter, woodruff cutter, hollow mill, dovetail cutter, or shell mill is attached to the spindle. The spindle and rotating milling cutter are configured to move in the 7′ direction. A machinist will bring the rotating milling cutter into contact with the work piece by moving the spindle in the Z direction or by moving the table in the X or Y direction until the rotating milling cutter intersects the work piece, cutting the work piece.
For a vertical milling machine, the movement of the table of the milling machine defines the X and Y-axes of the X-Y-Z coordinate system. The spindle defines the Z-axis and the machine tool is adjustable by the machinist so that the axis of rotation of the spindle is normal to the X and Y-axes defined by the table. The machinist may align the Z-axis to the X and Y-axes of the table using the squaring apparatus and method taught by U.S. Pat. No. 7,069,666 to Joseph Navarro, issued Jul. 4, 2006 and taught by U.S. Pat. No. 6,832,440 to Joseph Navarro, issued Dec. 21, 2004, which patents are incorporated by reference as if set forth in full herein. The squaring apparatus taught by U.S. Pat. Nos. 6,832,440 and 7,069,666 includes a shank that has a longitudinal axis. The shank can be attached to the spindle of the machine tool. A squaring apparatus body is attached to the shank. The squaring apparatus body supports two indicators in a spaced apart relation on either side of the longitudinal axis of the shank. The plungers of the two indicators are movable parallel to the longitudinal axis of the shank. After the two indicators are calibrated, the shank is attached to the spindle, the spindle is rotated until the spaced apart indicators are oriented along the X-axis, and the spindle is advanced until the plungers contact the table of the machine tool. The table is adjusted until both indicators have the same reading. The process is repeated for the Y-axis, squaring the table with respect to the spindle.
The machinist also must align the work piece with respect to the table so that when the table is moved along the X-axis or the Y-axis, the work piece moves in the desired orientation with respect to the milling cutter. Otherwise, the cuts made by the milling cutter will be in the wrong location on the work piece. One way to align the work piece and the spindle is to align the vise or other work-holding feature to the spindle using an edge finder. Once the spindle is aligned to the table and aligned with the work piece, the machinist must accurately locate the spindle with respect to the work piece using an edge finder.
The prior art does not teach the apparatus or method of the invention.